Electronic devices may generate heat due to resistance and or relatively poor electrical contact between the electronic device and a common metal junction. Inadequate attachment of the electronic device to the metal junction may further decrease the electrical contact therebetween. When the electronic device is better secured to the metal junction, the electronic device is capable of rejecting more waste heat, has better electrical contact and is more able to maintain a lower temperature.
The common metal junction may be, for example, a bus bar and the electronic device may be a transistor. A surface on the bus bar may abut a surface on the transistor to form an electrical and a thermal connection therebetween. The respective surfaces, however, are typically imperfect and may provide less actual contact between the respective surfaces (e.g., metal-to-metal contact). The imperfections, due to surface irregularities, may create a void (i.e., a volume of air) between the respective surfaces. Moreover, failure to adequately secure the transistor to the bus bar can further reduce contact therebetween. When there is less actual contact between the respective surfaces, there may be increased resistance and less electrical contact between the bus bar and the transistor, which may cause increased heating and may cause the transistor to fail.
Traditionally, an electrically conductive powder or paste is added between the transistor and the bus bar. The electrical conductivity of the powder or paste may be low relative to the respective metal surfaces of the bus bar and the transistor. Notwithstanding the low electrical conductivity, the powder or paste may fill the volume between the respective surfaces, which may relatively increase the area of contact and thus decrease the resistance between the bus bar and the transistor. The powder or paste, however, may dry and crack over time, which may once again introduce air pockets. The air pockets may reduce the actual contact between the transistor and the bus bar, thus increasing the resistance therebetween and diminishing the benefit of the powder or paste. Moreover, use of the powder or the paste in mass production may be undesirable because of handling or assembly issues.